As charged particle beam apparatuses each of which scans a charged particle beam acting as a probe on a sample surface and obtains an image of the area, there are a scanning electron microscope (SEM), a scanning ion microscope (SIM), a focused ion beam (FIB) processing apparatus, etc. In the general charged particle beam apparatus, while the charged particle beam acting as the probe is irradiated on the sample and is scanned in a field of view that is an observation area, electrons generated from the sample are detected. In the case where the detection object is electrons, an image corresponding to the scanned area is made generally by making signal electrons collide with a detector to convert them into an electric signal, measuring this electric signal in a predetermined time (a sampling time) by an analog to digital (A/D) converter to convert it to a digital signal, and plotting a summation result to a pixel corresponding to a scanning position of the charged particle beam. Incidentally, a sampling time interval is less than or equal to a time interval during which the charged particle beam scans one pixel. This is to prevent a meaningless pixel that may exist even when there is no sampling from existing.
As such a charged particle beam apparatus, there is a case where using the scanning electron microscope, top surface observation of the sample and observation of its internal structure are performed. As one that acquires both of information about a shape of a top surface in the sample and information about a shape inside the sample, an apparatus described in Patent Document 1 is known.
Patent Document 1 discloses a technique that detects the signal electrons by means of energy band pass filtering, assigns a color corresponding to the energy, and displays an image with brightness corresponding to a detected intensity using an energy selective detector of electric field shielding type that mounts an energy filter based on electric field shielding and an energy selective detector of orbital selection type utilizing a fact that the signal electrons take different trajectories depending on their energies. According to the energy filter of orbital selection type, detection of the signal electrons by the energy band pass filtering can be performed by a single image acquisition according to the number of arranged detectors, and performing image processing off-line makes it possible to output an SEM image only of a top surface that reflects information of only low-energy-loss back scattered electrons (BSE) and to output the SEM images of the top surface and of the inside of the sample that reflect BSE information of all the energy bands that are detected.